We utilize plantwide DC power set at 28 +/- 2 VDC. I^ve seen different power specifications from various DeviceNet product vendors, ranging from 11-30 VDC, 11-25 VDC and even 24 VDC ?10%. What are the true requirements?
Answered by Ray Romito, DeviceNet Trainer, e-mail: raromito@ra.rockwell.com
A83) The Specifications for power applied to the network is 24 VDC =/- 1%. The input voltage range for any given node is 11-25 VDC due to voltage drops along the power bus and tolerance stackups. The 5 volts between nodes is the common mode tolerance of the transceivers, which, if you stay within the stated bounds on current, voltage and cable distance, will not cause any problems.
What are the radiated/conducted RF field intensities DeviceNet products are expected to meet for CE marking?
Answered by Bob Lounsbury, Physical Layer Relounsbury@ra.rockwell.com
A84) DeviceNet products were generally subjected to the following levels: · Radiated Immunity: 10V/Meter · Conducted Immunity: 10V pk-pk · Radiated Emissions: CISPR Class A · ESD to 8kV air 4kV contact · Surge 2kV CM, 1kv DM · EFT 2kV
What is the minimum spacing that should be maintained between DeviceNet cables and 480 VAC power lines?
Answered by Bob Lounsbury, Physical Layer SIG, e-mail: Robert.Lounsbury@po.cle.ab.com
A104) If this application is in the United States or Canada, you should consult the National Electric Code book (NFPA 70) Article 725 subclause 54 or the CD Code book for Canada. For any other countries, you should consult the respective country electric codes. For the USA, NFPA 70-725-54 will set the basic restrictions on where the DeviceNet cable can be placed with respect to electric light and power lines. DeviceNet cables are Class 2 cables when applied to building wiring. If the cable tray is mounted on a machine and the cables do not leave the machine, then you should consult NFPA 79, Standards for Industrial Machinery. If you need a copy of the NEC book, it is available by calling (1) 800 344-3555. My overall recommendation is that the wires maintain a 3-inch separation or place a metallic barrier between the two sets of cables. This will provide adequate shielding from most high voltage transients.